The present invention relates to a thermnosensing probe for sensing rectal temperature of a patient. In particular, the present invention relates to rectal probe designs taking the form of a balloon thermosensing probe that includes an insertion lumen for allowing gas to escape from the rectum and for receiving an introducer to facilitate insertion of the balloon into the rectum, and alternatively or in combination a thermosensing device having a body made of open-cell foam which is capable of conforming to the shape of a rectal cavity into which it is inserted.
The prostate gland is a complex, chestnut-shaped organ which encircles the urethra immediately below the bladder and lies immediately adjacent the rectum. This relatively small organ, which is the most frequently diseased of all internal organs, is the site of a common affliction among older men, benign prostatic hyperplasia (BPH), as well as a more serious affliction, cancer. BPH is a non-malignant, bilateral nodular tumorous expansion of prostate tissue occurring mainly in the transition zone of the prostate. Left untreated, BPH causes obstruction of the urethra which usually results in increased urinary frequency, urgency, incontinence, nocturia and slow or interrupted urinary stream. BPH may also result in more severe complications, such as urinary tract infection, acute urinary retention, hydronephrosis and uraemia.
A fairly recent treatment method for BPH involves microwave thermal therapy, in which microwave energy is employed to elevate the temperature of tissue surrounding the prostatic urethra above about 45xc2x0 C., thereby thermally damaging the tumorous BPH tissue. Delivery of microwave energy to tumorous prostatic tissue is generally accomplished by a microwave antenna-containing applicator, which is positioned within a body cavity adjacent the prostate gland. The microwave antenna, when energized, heats adjacent tissue due to molecular excitation and generates a radiation pattern which encompasses and necroses the tumorous prostatic tissue. The necrosed intraprostatic tissue is subsequently reabsorbed by the body, thereby relieving an individual from the symptoms of BPH.
One type of thermal therapy treatment of BPH is transurethral microwave thermal therapy. This method of treatment positions a Foley-type catheter containing a microwave antenna within the urethra adjacent to the prostate gland. The microwave antenna is energized to heat and necrose a selected volume of tumorous prostatic tissue up to 2.0 centimeters from the urethra, by raising the temperature of the selected tissue to a temperature above about 45xc2x0 C. for a time sufficient to necrose the tissue.
Due to the relatively close proximity of the rectum to the urethra, it is critically important in the course of transurethral thermal therapy that the temperature of the rectum is maintained below a threshold temperature. Rectal temperatures greater than the threshold may cause significant damage to the rectum.
Typically, the temperature of rectal tissue adjacent the prostate is measured and monitored with a rectal temperature sensing probe. The probe supports one or more temperature sensing elements against a wall of the rectum adjacent to the prostate to provide the physician with essential information for controlling the location and degree of heat induced in the prostate. In providing a rectal probe to measure the temperature of rectal tissue adjacent the prostate, it is desirable to maintain the position of a temperature sensing device supported by the probe directly adjacent to the rectal wall to provide optimally accurate temperature readings. Rectal tissue should not be compressed by the temperature sensing probe, since compression tends to reduce blood flow and increase the susceptibility of the rectal tissue to thermal damage. Compression of rectal tissue also compresses the prostate, which reduces the distance between the urethra and the rectal wall and thereby increases rectal temperatures due to heat energy delivered from the urethra. The rectal probe should be easily insertable without deforming or causing trauma to rectal tissue, and should include means for ventilating gas built up in the rectum while the probe is inserted.
Many devices used to monitor the temperature of the rectal wall during thermal therapy involve the use of a balloon for anchoring temperature sensing devices in the rectal cavity. To operate these devices, a balloon is first inserted into the rectum, and is then inflated to engage the wall of the rectum and hold the temperature sensing devices in place. Proper use of this device requires human manipulation and care, introducing the risk of human error. For example, over-inflation of the balloon could potentially compress rectal tissue and thereby lead to overheating of rectal tissue as mentioned previously, or the balloon could break or inadvertently deflate. While balloon devices are effective for their purpose when properly utilized, an alternate design could potentially represent an improvement over the state of the art.
The present invention is a rectal thermosensing unit for sensing temperature of rectal tissue. The unit includes an elongate member having an inflation lumen extending therethrough. An inflatable balloon is supported by the elongate member. An interior of the inflatable balloon is in fluid communication with the inflation lumen. An insertion lumen extends through the elongate member, and an introducer is insertable into the insertion lumen. At least one temperature sensing device is supported by the inflatable balloon.
Another aspect of the present invention is a method of locating in a rectum a rectal thermosensing probe having an elongate member supporting an inflatable balloon, which in turn supports a temperature sensing device. An inflation lumen and an insertion lumen are provided, extending through the elongate member. An introducer is inserted into the insertion lumen. The inflatable balloon supported by the elongate member is inserted into the rectum. The introducer is removed from the insertion lumen, and the inflatable balloon is inflated by providing fluid through the inflation lumen.
Another form of the present invention is a rectal thermosensing unit having a passively expandable body with first and second ends. An elongate member supports the body between the first and second ends. A temperature sensing device is supported by the body, and a handle is attached to the elongate member at the second end of the body. In one embodiment, a sheath is deployable around the body to compress the body to a preselected diameter for insertion into a rectum.
The present invention also encompasses a method of sensing temperature of rectal tissue. A passively expandable body having an uncompressed outer diameter approximating a rectal cavity is compressed. The body carries at least one temperature sensor. The compressed body is inserted into the rectal cavity. The body is then allowed to passively expand to conform to a shape of the rectal cavity.
A still further aspect of the invention is a method of forming a rectal thermosensing unit. A passively expandable body is formed having an uncompressed outer diameter approximating a rectal cavity. A passageway is formed through the body, and an elongate member is bonded to the body in the passageway. A temperature sensing device is attached to the body, and a handle is either attached to or formed from the elongate member.